Cicadas are a unique group of insects recognized globally for the remarkable noise produced during their seasonal appearances. The male insects engage in a persistent, collective song that often dominates the summer soundscape in forested and suburban areas. This acoustic display is a survival mechanism, primarily functioning to attract mates and occasionally to deter predators. The sheer volume of this natural phenomenon frequently prompts the question of precisely how loud these small creatures can become.
Quantifying the Loudness of Cicada Songs
Cicadas hold the distinction of being some of the loudest insects in the world, capable of generating sound levels that rival loud human machinery. The record for the loudest single insect belongs to the African cicada, Brevisana brevis, which has been measured singing at 106.7 decibels (dB) when recorded from 50 centimeters away. This measurement distance is an important factor, as the perceived loudness drops significantly the further a listener moves away from the source.
North American periodical cicadas, such as those that emerge in 13- or 17-year cycles, also produce intense calls, with individual insects reaching 100 dB. Alarm calls from certain North American species, like Tibicen walkeri, have been measured as high as 108.9 dB. However, the overall noise from a dense chorus, heard at a greater distance, typically falls within the range of 80 to 85 dB. This variation highlights that the intensity experienced by a person depends heavily on their proximity to the singing insects.
The Biological Mechanism of Sound Production
The immense volume of the cicada’s song is achieved through a specialized anatomical structure found exclusively in males. This structure consists of a pair of ribbed, drum-like membranes called tymbals, which are located on the sides of the abdomen. Sound is generated when a powerful internal muscle rapidly contracts, causing the tymbal membrane to buckle inward.
Each inward buckle produces a distinct, sharp click. The muscle’s ability to contract and relax hundreds of times per second results in a rapid succession of these clicks, fusing them into the characteristic continuous, buzzing sound heard by humans. The cicada’s abdomen is largely hollow, acting as a natural resonating chamber that significantly amplifies the sound generated by the tymbals.
Hearing Risk and Comparative Noise Levels
The 100 dB level reached by many species is comparable to a motorcycle, a jackhammer, or a chainsaw. Health organizations consider sustained exposure to any sound above 85 dB to be potentially hazardous to human hearing. This threshold is relevant because a dense cicada chorus often meets or exceeds this intensity level.
Exposure to noise at 100 dB carries a substantial risk, with guidelines suggesting that hearing damage can occur after as little as 15 minutes of continuous exposure. This risk is generally confined to situations where a person stands directly beneath a tree full of chorusing males for an extended duration. The primary health concern is the potential for temporary or permanent noise-induced hearing loss and the onset of tinnitus, commonly known as ringing in the ears.
Risk is low during normal outdoor activity, but individuals concerned about prolonged periods in areas of high cicada density may choose to use earplugs or other hearing protection. Avoiding the peak singing hours, typically late morning to late afternoon, can also minimize exposure. Sound intensity dissipates quickly with distance, so moving away from the loudest source can reduce the decibel level substantially.